Although the present invention is useful in any adhesive composite needing a delivery system, it has particular benefit in connection with transparent film dressings and surgical drapes. These dressings and drapes are widely used as a protective layer over a wound, facilitating healing in a moist environment while acting as a barrier to liquids and bacteria. Dressings of this type are available under trade names such as Tegaderm.TM. (3M, St. Paul, MN) Bioclosure.TM. (Johnson & Johnson, New Brunswick, N.J.) and Op-Site.TM. T. J. Smith & Nephew, Hull, England). Uniflex.TM. (Howmedica, Largo, Fla.). U.S. Pat. No. 3,645,835, which is hereby incorporated by reference, describes one such moisture vapor permeable, water bacteria impermeable dressing.
The polymeric films used in such dressings are extremely thin, flimsy, and supple. They are supplied with a releasable protective liner overlying the adhesive coated surface of the film. When the liner is removed the adhesive coated film tends to fold and stick to itself forming wrinkles which render smooth aseptic application of a dressing or drape to skin very difficult. Various delivery systems have been proposed to obviate this problem.
One such delivery system utilizes a frame to support the edges of the film during its application. European Pat. Appln. No. 81 30 4905 describe a composite having a relatively thin polymeric film which is conformable to animal anatomic surfaces. A pressure sensitive adhesive is coated to at least a portion of one surface of the polymeric film. A release liner is attached to the adhesive coated surface of the film. A second releasable layer or carrier is attached to the opposing (exposed) surface of the film. This second releasable layer is attached to the film more tenaciously than the release liner is adhered to the adhesive side of the film and is preferably a frame adhered to the periphery of the film. In use the releasable layer stays with the film until the film is affixed to the substrate, at which time it may be removed.
Another delivery system is utilized in the Op-Site.TM. dressing. In that dressing the film is provided with a pull tab along one edge of the film. The releasable liner is removed by peeling the liner and the pull tab away from each other. The pictorial instructions supplied with the product suggest that the dressing should be applied by grasping the pull tab and the releasable liner which has been partially removed and then placing the film on the intended site. Thereafter the releasable liner is completely peeled off and the dressing smoothed to the skin surface. The pull tab can be left in place or, in an alternative embodiment, the pull tab and the film to which it is adhered are removed from the remainder of the dressing by separation along perforations provided for this purpose. U.S. Pat. No. 4,413,621 describes such a dressing.
A third delivery system is described in European Pat. Appln. No. 84 30 0752.7 (publication No. 0,120,570). That application describes a wound dressing made of a film that is coated on one face with a biocompatible adhesive. One or more liner sheets are releasably adhered to the adhesive coated surface. Release retarding means are provided along one edge or a pair of opposed edges of the dressing to require a greater force to separate the layers (film, adhesive, and liner) at the edge or edges than at the remainder of the contact area. The release retarding means may be a thicker strip of the polymeric film, a stiffer piece of film adhered to the film at its edges, a strip of liner backing wrapped around the edge of the film and adhered to the surface of the film, or a strip attached to the exposed surfaces of both the film and the backing. Alternatively an adhesive having greater tenacity than the quick release adhesion of the biocompatible adhesive for the liner may be used.